• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.14 no.3
• /
• pp.134-144
• /
• 2009

Paleoproductivity changes in the central part of the Bering Sea since the last glacial period were reconstructed by analyzing opal and total organic carbon (TOC) content and their mass accumulation rate (MAR) in sediment core PC23A. Ages of the sediment were determined by both AMS $^{14}C$ dates using planktonic foraminifera and Last Appearance Datum of radiolaria (L. nipponica sakaii). The core-bottom age was calculated to reach back to 61,000 yr BP. and some of core-top was missing. Opal and TOC contents during the last glacial period varied in a range of 1-10% and 0.2-1.0%, and their average values are 5% and 0.7%, respectively. In contrast, during the last deglaciation, opal and TOC contents varied from 5 to 22% and from 0.8 to 1.2%, respectively, with increasing average values of 8% and 1.0%. Opal and TOC MAR were low ($1gcm^{-2}kyr^{-1}$, $0.2gcm^{-2}kyr^{-1}$) during the last glacial period, but they increased (>5 and >$1gcm^{-2}kyr^{-1}$) during the last deglaciation. High diatom productivity during the last deglaciation was most likely attributed to the elevated nutrient supply to the sea surface resulting from increased melt water input from the nearby land and enhanced Alaskan Stream injection from the south under the restricted sea-ice and warm condition during the rising sea level. On the contrary, low productivity during the last glacial period was mainly due to decreased Alaskan Stream injection during the low sea-level condition as well as to extensive development of sea ice under low-temperature seawater and cold environment.

• Journal of Life Science
• /
• v.20 no.4
• /
• pp.487-495
• /
• 2010

A microorganism hydrolyzing carboxymethylcellulose (CMC) was isolated from seawater, identified as Psychrobacter aquimaris by analysis of 16S rDNA sequences, and named P. aquimari LBH-10. This strain produced an acidic carboxymethylcellulase (CMCase), which hydrolyzed carboxymethylcellulose (CMC), cellobiose, curdlan, filter paper, p-nitrophenyl-$\beta$-D-glucopyranoside (pNPG), pullulan, and xylan, but there was no detectable activity on avicel and cellulose. The optimal temperature for CMCase produced by P. aquimari LBH-10 was $50^{\circ}C$ and more than 90% of its original activity was maintained at broad temperatures ranging from 20 to $50^{\circ}C$ after 24 hr. The optimal pH of the CMCase was 3.5, and more than 70% of its original activity was maintained under acidic conditions between pH 2.5 and 7.0 at $50^{\circ}C$ after 24 hr. The optimal pH of CMCase produced by P. aquimaris LBH-10 seems to be lower than those produced by any other bacterial and fungal strain. $CoCl_2$, EDTA, and $PbCl_2$ at a concentration of 0.1 M enhanced CMCase-produced P. aquimaris LBH-10, whereas $HgCl_2$, KCl, $MnCl_2$, $NiCl_2$, and $SrCl_2$ inhibited it.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.28 no.1
• /
• pp.39-46
• /
• 2010

Sounding data is the essential source for the safety of ships navigation system, and fundamental to the reasonable usage and maintenance of the ocean as well. As IT tech, positioning equipment such as GPS and INS, echo sounder are developed, recently, the precise submarine topography database bas been built by Multi-Beam Echo Sounder. However, MBES data includes some inevitable error caused by several factor, and some data have errors where the terrain is wobble. The error, which causes the $moir\acute{e}$ pattern error is the main factor hindering the accuracy of MBES data results, and therefore it is necessary to figure out the main cause of the error for the improvement of the accuracy by removing error data. On this research, the main cause of the error data is studied by analyzing motion sensor value of data including the $moir\acute{e}$ pattern error. Thus, as the result of examination, it turns out that the $moir\acute{e}$ pattern error is related to the standard deviation of Roll, and error data values are results of the non-correspondence between Swath data and Roll values caused by the drastic change of Roll values. Accordingly, the error data is removed by comparing between the gradient of Swath data and Roll values. Finally, as the result of removing error data, it is expected to be able to estimate the quality of MBES using the standard deviation of Motion sensor's Roll value, and calculate the additive error factor, which minimize non-corresponding data, and also this research must be contributed to improve the accuracy of sounding for small vessels with lots of motion in the bad circumstance for navigation.

• Journal of the Korean earth science society
• /
• v.32 no.7
• /
• pp.750-760
• /
• 2011

In this study, the reproducibility of the simulated current climate by using two regional climate models, such as Seoul National University Regional Climate Model (SNURCM) and Weather Resuearch and Forecasting (WRF), is evaluated in advance to produce the standard regional climate scenario of future climate. Within the evaluation framework of a COordinated Regional climate Downscaling EXperiment (CORDEX), 28-year-long (1978-2005) regional climate simulation was conducted by using the Hadley Centre Global Environmental Model (HadGEM2-AO) global simulation data of the National Institute of Meteorological Research (NIMR) as a lateral boundary forcing. The simulated annual surface temperatures were in good agreement with the observation; the spatial correlation coefficients between each model and observation were over 0.98. The cold bias, however, were shown over the northern boundary in the both simulated results. In evaluation of the simulated precipitation, the skill was reasonable and good. The spatial correlation coefficients for the precipitation over the land area were 0.85 and 0.79 in SNURCM and WRF, respectively. It is noted that two regional climate models (RCMs) have different characteristics for the distribution of precipitation over equatorial and midlatitude areas. SNURCM shows better distribution of the simulated precipitation associated with the East Asia summer monsoon in the mid-latitude areas, but WRF shows better in the equatorial areas in comparison to each other. The simulated precipitation is overestimated in summer season (JJA) rather than in spring season (MAM), whereas the spatial distribution of the precipitation in spring season corresponds to the observation better than in summer season. Also the RCMs were capable of reproducing the annual variability of the maximum amount and its timing in July, in which the skills over the inland area were in better agreement with the observation than over the maritime area. The simulated regional climates, however, have the limitation to represent the number of days for extremely hot temperature and heavy rainfall over South Korea.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.6
• /
• pp.2401-2409
• /
• 2013

Reliability analysis with response surface method (RSM) was peformed for a offshore wind turbine (OWT) monopile, which is one of mostly used foundations under 25m seawater depth in the world. The behaviors of a real OWT monopile installed into sandy soils subjected to offshore environmental loads such as wind and wave were analysed using reliability design program (HSRBD) developed in KIOST. Sensitivity analysis of design variables for a OWT monopile with 6m diameter showed that the larger in pile diameter the smaller in probability of failure ($P_f$) of a horizontal deflection and a rotational angle at a pile top, but at a greater than 7m of pile diameter, the reduction rate of $P_f$ was almost constant. It is a necessary that appropriate local design criteria should be designated as soon as possible because there were significant differences on horizontal deflections; $P_f$ was 60% at a minimum criteria 15mm deflection, however, 1.5% $P_f$ when 60mm deflection using 1% of pile diameter from local design criterion standard. Finally, friction angle of sand among many design variables was found most influential design factor in OWT monopile design, and a sensitivity analysis is found an important process to understand which design variables can mostly reduce $P_f$ with a optimum design for maintaining OWT stability.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.6
• /
• pp.683-690
• /
• 2015

For demolition of offshore facilities, traditional methods such as jackhammer and explosive methods have been often used in construction industry. However, prohibitions for use of those methods are becoming more rigorous especially in environmentally and historically sensitive areas. It was also reported that the explosive demolition method on maritime bedrock can cause a disturbance of ecosystem. For those reasons, use of soundless chemical demolition agent(SCDA) is getting the spotlight. However, researches regarding the mechanical point of SCDA have seldom performed. There is no industrial standard for use of SCDA yet. In this study, a pilot experimental study in order to measure the required expansive pressure that could be generated from SCDA was conducted. Numerical models were developed in order to estimate the required expansive pressures of SCDA for initiating cracks depending on selected key parameters. Obtained results indicate that the required pressure does not decrease linearly as increasing the hole diameter, the number of holes, and the ratio of hole-distance to hole-diameter.

• 한국연소학회:학술대회논문집
• /
• 2014.11a
• /
• pp.253-254
• /
• 2014

지구온난화 문제는 한국가의 문제가 아니라 인류의 문제로 대두되어 많은 이에대한 많은 연구가 이루어 지고 있다. 지구온난화의 주 대상물질인 화석연료로부터 연소시 발생하는 이산화탄소를 감축하기위한 많은 규제와 노력이 요구된다. CCS(Carbon Capture & Storage)란 화석연료로 부터 연소시 대기 중으로 배출되는 온실가스($CO_2$)를 포집하여 재생 또는 지중, 해양에 저장하는 기술로서 국가녹색성장 핵심기술중의 하나로 분류되며, $CO_2$ 회수방안, 저장, 처리관련 연구를 비롯하여 국내외 적으로 활발한 연구가 이루어 지고 있다. 또한 순산소 연소기술을 통한 $CO_2$ 회수, 처리기술은 연료의 산화제를 공기대신 순도 95% 이상의 고농도 산소를 이용하여 순산소연소를 하며, 이때 발생하는 배가스의 대부분은 $CO_2$와 수증기로 구성되어 있다. 발생된 배가스의 약 70~80%를 다시 연소실로 재순환시켜 연소기의 열적 특성에 적절한 연소가 가능하도록 최적화함과 동시에 배가스의 $CO_2$ 농도를 80% 이상으로 농축시켜 회수를 용이하게 하며, 동시에 공해물질은 NOx 발생량을 10ppM 이하로 줄일 수 있는 기술이다. 천연가스를 생산하는 LNG기지에서 연소에 의한 이산화탄소를 발생시키는 기기로는 수중연소식기화기(SMV ; Submerged Combustion Vaporizer)를 들 수 있다. SMV는 버너를 이용하여 $-162^{\circ}C$ LNG를 $10^{\circ}C$의 LN로 기화시키는 설비로서 특히 동절기에 작동시키며 $CO_2$를 배출시키는 연소기다. 본 연구에서는 수중연소식 SMV에 순산소 연소방식을 적용하여 천연가스와 산소를 연소시키므로서 발생되는 $CO_2$를 LNG냉열을 이용 액체화 시켜 회수하는 연구를 수행하고 있다. 내용중에 수중연 소식 SMV에 대한 순산소 연소기를 개발하는 연구를 수행하였으며, 실제 SMV의 1/10크기, 열량기준 1/900로 모형을 제작하여 실험하였다. 연소기 노즐 은 직경 0.6mm, 배가스가 수조내에서 48개의 노즐을 제작하였다. 실험결과 일정량 이상의 $CO_2$ EGR율이 일정 값 이상이 되면 화염의 길이가 공기/NG 화염 길이와 큰 차이가 없었으며 $CO_2$ EGR율이 100%이상에서는 $CO_2$ EGR율 증가에 따른 화염길이 변화는 크게 나타나지 않았다. CO 배출 농도는 공기/NG 연소의 경우보다 높게 나타났으며, ${\lambda}$가 1.4보다 높은 조건에서는 측정되지 않았다. NOx의 배출 농도는 약 1~8ppm으로 나타났다.

• Journal of Applied Biological Chemistry
• /
• v.59 no.3
• /
• pp.265-271
• /
• 2016

Recently, liver damage contributes to big percentage of the morbidity and mortality rates worldwide. Excessive intake of alcohol is one of the major causes of liver injury. When liver injury is repeated and becomes chronic, it leads to development of fibrosis and cirrhosis. In the liver, TGF-${\beta}$ is a profibrogenic cytokine, which participates in various critical events cause liver fibrosis. Seahorse (Hippocampus abdominalis) is a common traditional Chinese medicine and has been widely used for centuries. Seahorse has been known to have a variety of bioactivities, such as anti-oxidant, anti-fatigue, and anti-tumor. Peptide is one of the main compounds of seahorse. In this study, we isolated enzymatic hydrolysate from seahorse H. abdominalis by alcalase hydrolysis and investigated the effect of the hydrolysate on liver injury. In the present in vitro studies, the hydrolysate increases cell viability of Chang cells and protects Huh7 cells from ethanol toxicity. In addition, the hydrolysate inhibits TGF-${\beta}$-induced responses. In vivo studies show that the pretreatment of hydrolysate reduces alcohol-induced increases of serum Glutamic oxaloacetic acid transaminase and Glutamic pyruvate transaminase activities and increases liver weight and body weight. These results suggest that seahorse may have a hepatoprotective effect.

• Microbiology and Biotechnology Letters
• /
• v.44 no.2
• /
• pp.156-162
• /
• 2016

In this study, we isolated a new agar-degrading marine bacterium and characterized its agarase. An agardegrading marine bacterium SH-1 was isolated from seawater, collected from the seashore of Namhae in Gyeongnam province, Korea, and cultured in marine agar 2216 media. It was identified as Maribacter. sp. SH-1 by phylogenetic analyses, based on 16S rRNA gene sequence. The extracellular agarase was extracted from culture media of Maribacter sp. SH-1 and characterized. Its relative activities were 56, 62, 94, 100, and 8% at 20, 30, 40, 50, and 60℃, respectively, whereas 15, 100, 60, and 21% relative activities were observed at pH 5, 6, 7, and 8, respectively. Its extracellular agarase exhibited maximum activity (231 units/l) at pH 6.0 and 50℃, in 20 mM Tris-HCl buffer. Therefore, this agarase would be applicable as it showed the maximum activity at the temperature at which the agar is in a sol state. Furthermore, the agarase activities remained over 90% at 20, 30, and 40℃ after 0.5 h exposure at these temperatures. Thin layer chromatography analysis suggested that Maribacter sp. SH-1 produces extracellular β-agarase, as it hydrolyzes agarose to produce neoagarooligosaccharides, such as neoagarohexaose (34.8%), neoagarotetraose (52.2%), and neoagarobiose (13.0%). Maribacter sp. SH-1 and its β-agarase would be useful for the production of neoagarooligosaccharides, which shows functional properties, like skin moisturizing, skin whitening, inhibition of bacterial growth, and delay in starch degradation.

• Journal of the Society of Disaster Information
• /
• v.16 no.2
• /
• pp.276-290
• /
• 2020

Purpose: The construction history of domestic port facilities has been more than 100 years, and until recently, modern facilities have been continuously built and expanded. However, it is not easy to keep the required performance conditions at the time of initial construction due to changes in the marine environment and increase in volume. In particular, in the case of harbor structures that have a long service life, safety performance and function management are becoming very important due to the increase in the size of ships, the increasing frequency of use, and the increase in the scale of natural disasters. Method: Therefore, this study investigates the state change by structural type of port facilities and analyzes the rehabilitation activities and the history that contribute to the performance improvement and life extension activities. Result: Through this, we distinguished between performance improvement cost (CAPEX) and repair maintenance activity (OPEX) that can be used to establish port facility maintenance strategy, and suggested cost model that can be used to establish maintenance strategy. Conclusion: These studies are expected to contribute greatly to mid- to long-term investment decisions.